Smokers are well known to be at elevated risk of cardiovascular disease and thrombosis. Thrombomodulin is a key regulator of blood clotting. Oxidation of methionine 388 in thrombomodulin greatly slows the rate at which the thrombomodulin-thrombin complex activates protein C, which, upon activation, slows clot formation. Smoking is known to impose an oxidative stress on the body. The hypothesis to be further confirmed is that oxidation of this methionine in thrombomodulin is elevated in smokers relative to non-smokers. Work will be done to improve the process of isolating thrombomodulin from urine. Further development of chromatographic methods using a new chromatographic system in order to improve chromatographic resolution and signal to noise ratios will also be undertaken. These improved methods will be used to test the oxidation levels of more smokers and non-smokers. PUBLIC HEALTH RELEVANCE: We are working to determine the extent to which a protein, thrombomodulin, which regulates blood clotting, is more modified in smokers than non-smokers. The leading cause of premature death in smokers is heart disease, and this may be related to the fact that the blood of smokers is more prone to clot than non- smokers perhaps partly because of greater modification of this protein in smokers.